1. Field of the Invention
This invention relates generally to slide fasteners and more particularly to such slide fasteners as are suitable for fluid-tight applications.
2. Description of the Prior Art
There have been proposed numerous types of fluid-tight slide fasteners for use on for example diving suits, life jackets and other articles requiring hermetic seal against leakage.
A typical known fluid-tight slide fastener comprises a pair of stringers each having a support tape resistant to leakage and a row of coupling elements mounted on one longitudinal edge of the tape, the stringers being coupled and uncoupled by a slider. To establish fluid-tightness of the slider, the longitudinal edge of the support tape is folded around the row of elements and the thus folded tape edge is externally enveloped by a row of sealing clamps positioned in registry with corresponding individual elements. Each of the confronting edges of the respective tapes includes a vertical rise portion extending between the folded portion and the flat tape web, the rise portion being relatively long (as shown in FIGS. 5 and 6 of the accompanying drawings illustrating a prior art example) so as to allow smooth, unrestricted movement of the slider. This prior art fastener however is vulnerable because the rise portions of the tapes being relatively long tend to crush apart or split under the influence of vertically exerted pressures as indicated by dotted lines in FIG. 5, where the flat tape webs at their respective ends are bonded to backing strips.
There is another prior art example of fluid-tight slide fastener in which the rise tape portions referred to above are relatively short so as to eliminate the possibility of the tape crushing apart or splitting, but this example makes it unsmooth, if not difficult, for the slider to move along in normal operation of the slide fastener.